"Perhaps most likely to raise some eyebrows is that Ubuntu 13.04 will let users purchase music or apps directly from the desktop Dash, without having to open a browser or a separate client." That's going to go down well.

Mark Shuttleworth, from day one of Ubuntu's existence has feigned community values, but is yet another commercial predator who used his considerable wealth and resources to buy market share for the purpose of gaining effective ownership and control of the core of mainstream GNU/Linux. All the while nearly destroying the true, collaboratively involved free software community by being a good-enough free (as in beer) solution. Indeed, the very name "Canonical" means "Core or Standard".
It makes little difference whether today's Ubuntu allows opting out of such and such intrusive privacy predator functions. Eventually they'll prevail as they wear out all of their balking core users, who will ultimately give in because it's too inconvenient (too much work) to be appropriately vigilant to hold off the thousands upon thousands of cuts inflicted by a motivated predator who is constantly looking for a way in. Then, when a sustainable (tipping point) market share of subservient, defeated users is reached, all opt-out options will disappear. It's a done deal.
So too, with other up and coming commercial distros. Given enough momentum and market share, they all get to feeling they can bend the sheep over (at least some of them) for a few lucrative, barbed and bloody poke-n-strokes up their hinder parts. One need only reflect on the wasteland of startup distros that claimed "We'll always be free!", only to renege when they started gaining momentum (perceived critical mass).
Ubuntu's been progressively moving to some version of an ad supported/private ecosystem model at the progressively higher and higher cost of their users privacy with each iteration. Even though today you're still not having to whip out your credit card to use Ubuntu, there's nothing free about it anymore, in principal or otherwise. Privacy has cash value and it's the price you must now pay. Ubuntu is too expensive now at the cost of your privacy. So it's time to move on, those of you who are able. To the rest of you who aren't able? It's time to bend over and grease up cause ol' Mark Shuttleworth has your backsides earmarked for invasion.

All said, the die seems to be cast, long suffering and utterly unbreakable. The commercial Linux distros will likely continue to attempt to emulate some form of the current proprietary mainstream revenue models, albeit on the quiet while interjecting as much subterfuge as can be reasonably absorbed by thinking beings without they're overtly being called bald-faced liars.

What of the community distros such as Debian etc..? They'll likely continue their wholly principled but mainstream end-user unusable work product in blissful perpetuity, building the core bits that keep the predators in almost salable software with which to launch yet another "FREE" (ah-hem) distro.

Welcome to GNU/Linux: Just one more venue for the 21st century's ongoing "What-Sucks-the-Least Choices", for 2013 and beyond.